Assessment of food based enrichment in collared anteater (Tamandua tetradactylla) by non-invasive monitoring of adrenocortical activity

EGUIZABAL G; PALME R; VILLARREAL D; DAL BORGO C; DOMINCHIN MF; BUSSO JM

Viena

Conferencia; Non-Invasive Hormone Monitoring Conference; 2012

International Society of Wildlife Endocrinology and Institute of Biochemistry of the University of Veteriary Medicine Vienna, Austria

Captive environments offer few opportunities for foraging or feeding and can negatively affects animal welfare. Measuring adrenocortical activity is a standard approach to evaluate stress and welfare in mammals. This study was conducted to: 1) physiologically validate an 11-oxoaetiocholanolone EIA, measuring faecal cortisol metabolites (FCM) with a 5ß-3a-ol-11-one structure to monitor adrenocortical activity in collared anteater faeces, and 2) investigate the influence of food-based enrichment on adrenocortical activity. Females (n=3) and males (n=2) were studied at Cordoba Zoo (Argentina). Faeces were individually collected (44 days) during pharmacological tests. The adrenal cortex was stimulated by ACTH (5 IU/kg, i.m., 10th day), then suppressed by dexamethasone (0,1 mg/kg, i.m., 37th day). After steroids were extracted from samples, FCM were measured by EIA. Due to great individual variation in defecation frequency (2-8 faeces per week), measurements were individually pooled in pre-ACTH, post-ACTH, pre-dexa and post-dexa groups. Data were transformed to rank and non-parametric Friedman ANOVA was performed. Faecal cortisol metabolites levels were different among groups (post-ACTH mayor pre-ACTH and pre-dexa mayor post-dexa; p menor 0,0001). Three months later, adrenocortical activity response to enrichment was monitored (three faeces/week) during three 6-week periods. The first period was used as FCM baseline (control); then (2nd period) animals were daily subjected to food-based enrichment (i.e. ants, fruits, yogurt). Finally, regular feeding was again provided. A linear mixed statistical model was applied. No differences were detected on average (3,91±0,35, 3,44±0,22 and 4,51±0,35 μg/g, respectively). However, the number of FCM peaks/period was significantly reduced by enrichment (p=0,02, F2,6=7,79). Peaks were defined on an individual basis as values that exceeded the control period mean plus 75th-percentile. Overall, results indicate that a non-invasive approach was validated to measure stress responses. This method has enormous potential for investigating different types of enrichment in this South American endemic xenarthra species.